Divide by a Fraction
Date: 03/19/97 at 18:05:06 From: James Farrell Subject: Divide by a Fraction Dear Dr. Math, How do you divide a whole number by a fraction? Consider: 5 -------- 1 --- 2 If you express it as: 5 --- 1 5 2 -------- = --- x --- = 10 1 1 1 --- 2 Why did I end up with 10? I'm sure the answer should be 2.5. Where did I go wrong? Thanks, Tim Farrell
Date: 03/21/97 at 04:19:54 From: Doctor Mitteldorf Subject: Re: Divide by a Fraction Dear Tim, Lots of people find this confusing. If you divide 5 by 2, the answer is 2.5. If you divide 5 by 1/2, do you expect the same thing as dividing by 2? If you divide by a number bigger than 1, it always reduces the number. If you divide by 1, it doesn't change anything. Does that make you think that dividing by a fraction less than 1 should INCREASE the number? How many kids can you serve with 5 cookies if each kid gets 2 cookies? You can serve 2 kids (with enough left over for 1/2 a kid). How many kids can you serve with 5 cookies if each kid gets 1/2 a cookie? That's 5 divided by 1/2. -Doctor Mitteldorf, The Math Forum Check out our web site!
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